Spawns a fly familiar that orbits Isaac, blocking enemy shots. If Isaac takes damage, this fly will seek out nearby enemies and attack them for the current room.
The fly always deals 1.5 damage per tick or 22.5 damage per second on contact with enemies.
The fly always deals 1.5 damage per tick or 6.4 damage per second on contact with enemies.
This item belongs to the Beelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.
Notes
This item has a 1% chance to drop when defeating Min-Min.
Smart Fly does not take up one of the three orbital slots; it floats between two of the other orbitals.
While behaving like an orbital, Smart Fly will break away from Isaac if he is traveling fast enough and will follow Isaac until he slows down enough to reattach. This is the only orbital item in the game that exhibits such behavior.
Interactions
Duct Tape: Fly will stay in place when orbiting Isaac but will still pursue enemies.
The fly always deals 1.5 damage per tick or 22.5 damage per second on contact with enemies.
The fly always deals 1.5 damage per tick or 6.4 damage per second on contact with enemies.
Beelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.
This item has a 1% chance to drop when defeating 
Min-Min.
Duct Tape: Fly will stay in place when orbiting Isaac but will still pursue enemies.
Beelzebub 
The Binding of Isaac: Rebirth
